Posts Tagged: UC Davis Department of Entomology and Nematology

What are the indirect effects of parasites and pesticides on pollination service?

Ecologist Sandra Gillespie, a postdoctoral researcher in the Neal Williams lab, UC Davis Department of Entomology and Nematology, will present the results of her research at a departmental seminar from 12:10 to 1 p.m., Wednesday, Oct. 16 in 122 Briggs Hall. It will be recorded for later posting on UCTV.

“Whether in natural or agro-ecosystems, researchers are increasingly viewing positive interactions such as pollination in a broader context rather than as isolated pair-wise interactions,” Gillespie says. “In natural ecosystems, my research has explored how incidence of parasites and diseases of native bumble bees may affect pollination of plants in old-field meadows in Massachusetts. High incidence of certain parasites reduced pollination of bumble bee-dependent wild plants, suggesting that parasitism may impact pollination service to native plants and crops.”

“In a more applied context, I examined the effects of field management decisions, including pesticide use and irrigation practices, on pollination service in onion seed production in California. High insecticide use, even pre-bloom, as well as reduced irrigation negatively impact pollinator visitation in this crop, highlighting the importance of considering the indirect effects of management on the pollination process in agro-ecosystems.”

Gillespie delivered a similar presentation at 2012 meeting of the Pacific Branch of the Entomological Society of America.

Gillespie, a postdoctoral researcher at UC Davis since 2011, received her bachelor’s degree in biology from Simon Fraser University, Canada, and her doctorate in both entomology and organismic and evolutionary biology from the University of Massachusetts, Amherst.

As a postdoc in the Williams lab, Gillespie is examining the mechanisms behind yield declines in hybrid onion seed production in California, with the goal of developing sustainable recommendations for producers.

Gillespie will be leaving UC Davis the first week of December; she has accepted a position at Simon Fraser University (starting Jan. 1) to work as a postdoc with Elizabeth Elle in the biology department. "I'll be studying pollinator-mediated selection in a community and landscape context," she said.

Her research on “Factors Affecting Parasite Prevalence among Wild Bumble Bees,” was published in Ecology Entomology, 2010. She has also published her work in the American Journal of Botany (“Variation in the Timing of Autonomous Selfing among Populations that Differ in Flower Size, Time to Reproductive Maturity, and Climate,” 2010) and Annals of the Entomological Society of America (“Laboratory Rearing of North American Tiger Beetles (Coleoptera, Carabidae: Cicindelinae,” 2011).

Pending publication in the Journal of Economic Entomology: “Insecticide Use in Hybrid Onion Seed Production Affects Pre- and Post-Pollination Processes,” the work of Gillespie, Neal Williams, Rachael Long and Nicola Seitz.

Jay Evans, a research entomologist with the USDA's Agricultural Research Service (USDA-ARS) Beltsville Bee Research Laboratory for the past 14 years, will discuss "Bee Disease Resistance and Colony Health" on Wednesday, Oct. 2 to open the fall seminar series hosted by the UC Davis Department of Entomology and Nematology.

His lecture, open to all interested persons, is from 12:10 to 1 p.m. in Room 122 of Briggs Hall, located on Kleiber Hall Drive, UC Davis campus.

"Honey bees are vulnerable to poor nutrition, parasites and pathogens, and exposure to chemicals," Evans said. "These threats can occur in batches and little is known about the impacts of multiple challenges to honey bee health, and about the abilities of bees to fend off these threats. I will present recent work aimed at determining the impacts of multiple parasites on bee health. I will also discuss the impacts Varroa mites, chemicals, and bacterial symbionts on bee health and colony losses."

As a research entomologist, Evans has focused his projects on a range of bee pests including bacteria, fungi, viruses and, mites, and beetles. He is especially interested in the immune defenses of bees toward these threats.

Evans was an early proponent of the Honey Bee Genome Project and helped recruit and organize scientists interested in applied genomics for bees. He has improved and applied genetic screens for possible causes of colony collapse disorder and is now heading a consortium to sequence the genome of the Varroa mite in order to develop novel control methods for this key pest.

Evans holds a bachelor's degree in biology from Princeton and a doctorate in biology from the University of Utah.

The fall seminars, coordinated by faculty members Joanna Chiu and Brian Johnson, will be held every Wednesday noon through Dec. 11 in 122 Briggs Hall, except for Nov. 27, Thanksgiving Week, when no seminar will be held.

Under the coordination of professor James R. Carey, all seminars are to be videotaped and posted at a later date on UCTV.

Honey bee guru Eric Mussen never misses an opportunity to talk about the importance of honey bee nutrition

It's critical issue.

Mussen, an Extension apiculturist based at the UC Davis Department of Entomology and Nematology since 1976, says malnutrition is a major factor in the declining bee population. That, along with pesticides, pests, diseases and stress.

"You, no doubt, have lost track of how many times I have stated that malnutrition is a leading factor in our unacceptable annual bee colony loss numbers," Mussen writes in the latest edition of his bimonthly newsletter, from the UC Apiaries, available free on his website.

"I have also stated innummerable times that our synthesized bee diets just cannot match the value of nutrients obtained by bees from a mixture of quality pollens. My concern has been that although we have a very good idea of the protein requirements for honey bees, the rations of essential amino acids honey bees require, and their required vitamins and minerals, etc., we still cannot feed bees on our best diets and keep them alive more than two months in confinement."

"Thus, we are missing some very critical components in our synthesized diets. If we could find those components, could we formulate a diet that would sustain bees in a healthy condition during 'feedlot beekeeping'?"

Mussen touches on a recent study that shows a component in honey, p-coumarin, stimulates "the honey bee immune system to work better."

However, it's not the honey that's doing this.

"Actually," Mussen says, "that chemical is a contaminant of honey that comes from pollen grains that are mixed into the honey during the bees' processing cycle. Thus, the bees need only to consume the pollen to obtain the desired results. How many other minor chemicals are there in pollens that are so useful to honey bee health?"

You'll want to read what he says about floral pollens containing microbes. "If these microbes are really so important to the nutritional needs of honey bees, what are we doing when we introduce antibiotics and fungicides into the system?"

Bottom line: we need more research to see what's going on with pesticide exposures and reduced microbial levels.

Or as Mussen says: "As researchers continue to try to improve upon our supplemental bee feeds, they have to consider the possibility of inoculating a semisold formulation of the diet with fresh pollen and stored pollen so that a natural microbial complex can do its things and make the food appropriately fit for consumption by honey bees."

Thorp, emeritus professor of entomology, says the distinctively marked bumble bee has the most restricted range of any bumble bee in the world. Its habitat is--or was--a small area of southern Oregon (Douglas, Jackson and Josephine counties) and northern California (Siskiyou and Trinity counties).

Scientists believe it may be as extinct as the Xerces butterfly. For, despite multiple trips to that area annually, Thorp hasn't spotted Franklin's bumble bee since 2006. Once quite prevalent, its population has severely declined since 1998.

Thorp sighted 94 in 1998; 20 in 1999; 9 in 2000 and only 1 in 2001. Sightings increased slightly to 20 in 2002, but dropped to 3 in 2003. Thorp saw none in 2004 and 2005; one in 2006; and none since. Now scores of people from all walks of life are looking for it, but no one has found it.

Franklin's bumble bee is one of several insects on the worldwide list. The other species include several butterflies, Actinote zikani, Parides burchellanus andPomarea whitneyi; the Seychelles Earwig (Antisolabis seychellensis); Beydaglari Bush-cricket (Psorodonotus ebneri); and a damsel fly (Risiocnemis seidenschwarzi).

It's truly a shame that our planet's next generation may never see such critters as Edward's pheasant, Attenborough's Pitcher plant and the Amsterdam Island albatross.

Or Franklin's bumble bee.

Robbin Thorp with his computer screen showing a photo he took of Franklin's bumble bee, one of the world's 100 most endangered species. (Photo by Kathy Keatley Garvey)

Robbin Thorp with his computer screen showing a photo he took of Franklin's bumble bee, one of the world's 100 most endangered species. (Photo by Kathy Keatley Garvey)

This macro image of Franklin's bumble bee is the work of Robbin Thorp.

This macro image of Franklin's bumble bee is the work of Robbin Thorp.

Their work "clearly demonstrates that at least five and as many as nine species of tropical fruit flies, including the infamous Medfly, are permanently established in California and inexorably spreading, despite more than 30 years of intervention and nearly 300 state-sponsored eradication programs aimed at the flies," wrote Pat Bailey in a UC Davis News Service story released today.

The findings, Bailey pointed out, have "significant implications for how government agencies develop policies to successfully manage pests that pose a threat to California's $43.5 billion agricultural industry."

Carey, an international authority on fruit-fly invasion biology, told her that "Despite due diligence, quick responses, and massive expenditures to prevent entry and establishment of these insects, virtually all of the fruit-fly species targeted by eradication projects have been reappearing in the same locations — several of them annually — and gradually spreading in the state."

Carey, Papadopoulos and Plant detailed the problem in the opening paragraph of their meticulously researched paper: "Since 1954 when the first tropical tephritid fruitfly was detected in California, a total of 17 species in four genera and 11,386 individuals (adults/larvae) have been detected in the state at more than 3348 locations in 330 cities." That's three out of four California cities.

Michael Parrella, professor and chair of the UC Davis Department of Entomology and Nematology: "The study has dramatic implications for California agriculture and the state’s international trading partners, and speaks to the urgent need to alter current eradication policies aimed at invasive species."

Frank Zalom, UC Davis entomology professor and incoming president of the 6500-member Entomological Society of America: “This study deserves serious consideration, and I hope that it helps lead to new discussions on a long-term approach for dealing with fruit flies and similar exotic pests by the United States and international regulatory authorities."

Former UC Davis chancellor Ted Hullar (1987-1994), one of the first to believe in "the science" that Carey presented, said: “From our first conversation, Jim struck me as a serious-minded guy, with strong ideas and clear focus, pursuing his insights and beliefs no matter the struggle. Good science and progress comes from that, making new paths in tough terrain, believing in the power of journey, as well as goal.”

The Medfly, smaller than a house fly, was first detected in California in 1975. It's considered the world's worst agricultural insect pest due to its wide distribution, wide range of hosts (its larvae infest more than 260 fruits and vegetables), and its ability to tolerate cool climates.

The Medfly prefers such thin-skinned hosts as peach, nectarine, apricot, avocado, grapefruit, orange, and cherry. The female may lay one to 10 eggs per fruit or as many as 22 eggs per day. She may lay up to 800 eggs during her lifetime, but usually about 300.

We remember when the Medfly wreaked economic havoc in the Solano County city of Dixon in September 2007. We were there.

At the time, Carey told us that "this may be just one of many isolated pockets of medfly infestations in California. This is really serious because the invasion process is so insidious."

The Medfly has been multiplying and spreading undetected--like cancer--for years, he said. "It may be a symptom of a much larger problem. But any way you look at it, this is the first really big outbreak in the Central Valley."

CDFA set up a command center at the Dixon May Fair and imposed a 114-mile radius quarantine of fruits, vegetables and nuts. Dixon was deep in the throes of tomato and walnut harvesting. The owner of a 65-acre organic produce farm that ships to 800 clients worried that he might lose $10,000 a week in potential sales.

Among the actions that the California Department of Food and Agriculture (CDFA) took at the onset:

Stripped all fruit from trees within a 100-meter radius of all Medfly finds

Ground-sprayed the organic compound Naturalyte (the active ingredient is Spinosad, a naturally occurring product of a soil bacteria) within a 200-meter radius of all Medfly finds

Set 1,700 fruit fly traps within an 81-square mile grid in all of Dixon and the surrounding area from near the Yolo County border to Midway Road

Began aerially releasing 1.5 million sterile male medflies (dyed pink for easy detection) over a 12-square mile area on Sept. 14, with weekly releases of 3 million medflies scheduled for at least nine months

Set up a yearlong command center, with four portable buildings and a task force of 25, on the Dixon May Fair grounds

Fast forward to today. Now that the Medfly has been declared a "permanent resident," what's next?

Carey agrees that “CDFA needs to continue to respond to outbreaks as they occur, but he advocates long-term planning based on “the science” that the insects are established. This includes heightened monitoring levels for the agriculturally rich Central Valley, an economic impact study, risk management/crop insurance, cropping strategies, fly fee zones/post harvest treatments, emergency/crisis planning, genetic analysis and a National Fruit Fly Program.

“Inasmuch as the Mediterranean, Mexican, Oriental, melon, guava and peach fruit flies have all been detected in the Central Valley, monitoring this incredibly important agricultural region should be increased by 5 to 10-fold in order to intervene and suppress populations and thus slow the spread,” Carey says.

“These pests cannot be wished away or legislated out of existence. Policymakers need to come to grips with this sobering reality of multiple species permanently established in our state in order to come up with a long-term, science-based policy for protecting agriculture in our state.”

(See James Carey's website for links to his work on fruit fly invasion.)